Sulfated polysaccharides isolated from the green seaweed Caulerpa racemosa plays antinociceptive and anti-inflammatory activities in a way dependent on HO-1 pathway activation.

Objective: Marine algae are abundant sources of sulfated polysaccharides with various biological activities. Consequently, their biomolecules are of great of commercial interest. In this study, we investigated the potential antinociceptive activity of a sulfated polysaccharide obtained from the green seaweed Caulerpa racemosa (CrII) and the involvement of the hemoxigenase-1 (HO-1) pathway in its anti-inflammatory effect.

Methods: We used a systemic evaluation to verify possible toxic effects of Crll after consecutive treatments. Swiss mice and Wistar rats were used for all experiments.

Results: In Swiss mice, CrII (0.01, 0.1 and 1.0 mg/kg) significantly reduced the number of abdominal contortions and the duration of paw licking in the second phase after treatment with acetic acid and formalin, respectively. However, CrII was unable to prolong the reaction time of thermally stimulated animals. The anti-inflammatory effect of CrII (0.01, 0.1 and 1.0 mg/kg) was evidenced by a decreased number of leukocytes in the peritoneal cavities of the rats. CrII (0.01, 0.1 and 1.0 mg/kg) also reduced the amount of paw edema induced by carrageenan (Cg) and dextran. The anti-inflammatory effect of CrII was confirmed by reduced levels of myeloperoxidase in the paw tissue of the Cg groups. After inhibition with ZnPP IX, a specific HO-1 phenotype inhibitor, the anti-inflammatory effect of CrII was no longer observed in Cg-induced paw edema tests. Consecutive Crll (1.0 mg/kg) for 14 days did not change any biochemical or histopathological parameters, or cause mortality of mice.

Conclusions: CrII did not produce any signs of toxicity and effectively decreased nociception and inflammation. Also, the anti-inflammatory effect of Crll is at least in part dependent on the integrity of the HO-1 pathway.